Strategic Support Package: Engineering of Active Materials by Multiscale/Multiphysics Computational Mechanics

连续介质力学描述了固体和流体系统在载荷作用下的响应。连续介质力学的基本假设是物质可以看作是一个连续的分布。这种世界观被称为宏观的，并为工程界提供了良好的服务，允许进行复杂结构的虚拟设计。然而，近年来，微观尺度的结构工程已经变得无处不在。应用包括计算机处理器、医疗设备、蜂窝技术等。随着元件和器件的尺寸减小到微观尺度甚至更远，经典的连续介质假设变得不那么有效。也就是说，物质的离散性质开始发挥作用，产生尺寸效应。经典的连续体公式没有长度标度，无法预测尺寸效应。因此，基于这些连续统公式的计算机模型(通常是有限元模型)的工程价值是有限的。活性材料--当受到非机械场作用时改变其结构的材料--在工程上有许多应用，例如，作为人工肌肉或作为执行器。材料与外加电场之间的相互作用导致了一个耦合问题。这里提出的研究将开发耦合问题的配方，以使下一代活性材料具有根据功能定制的优化的宏观和微观结构形式。与机械耦合的场包括热场、电场、磁场和化学场。要优化材料的微观结构，必须有一个健壮而准确的连续介质模型来捕捉尺寸效应。连接宏观和微观尺度将使用一类新的用于耦合问题的微观到宏观过渡技术-也称为计算均化。其基本思想是从宏观尺度向下传递有关载荷的信息，然后在微观尺度上解决一个问题，该问题捕捉到引起耦合和尺寸效应的所有关键特征。然后，平均(均化)的响应被返回到宏观尺度。按照这种方法，可以避免对微观结构的粗略假设，从而产生更准确和更具预测性的模拟。然而，跨尺度的多个领域的耦合是非常具有挑战性的，需要开发新的算法和连续统公式。最优化理论允许人们设计一个部件，使其在各种约束下最大化某个感兴趣的功能。这一理论对于宏观层面的工程产品来说是比较成熟的。微观层面并非如此，多尺度产品设计当然也不是这样。从微观尺度上优化设计和设计活性材料的能力将导致产品功能和设计的阶段性变化。这项研究的目的是通过先进的算法和计算模型实现这场革命。除了所述的科学目标外，这项研究还将支持建立一个新的计算工程和发现卓越中心。该中心旨在通过在组织研讨会和研讨会方面发挥主导作用，以及通过教育和发展研究生研究人员来促进英国的机械学。

Continuum Mechanics describes the response of solid and fluid systems subject to loading. The primary assumption of Continuum Mechanics is that matter can be viewed as a continuous distribution. This view of the world is termed macroscopic and has served the engineering community well, allowing for the virtual design of complex structures. In recent years, however, the engineering of structures at the microscopic scale has become ubiquitous. Applications include computer processors, medical devices, cellular technology, among others. As the size of components and devices decrease to the microscopic scale and beyond, so the classical continuum assumptions become less valid. That is, the discrete nature of matter starts to play a role giving rise to size effects. Classical continuum formulations do not possess a length scale and are unable to predict size effects. Thus, computer models based on these continuum formulations (typically finite element models) are of limited engineering value.Active materials - materials that change their structure when subjected to a non-mechanical field - have numerous applications in engineering, for examples, as artificial muscles or as actuators. The interaction between the material and the applied fields gives rise to a coupled problem. The research proposed here will develop formulations for coupled problems to enable the next generation of active materials with optimised macrostructural and microstructural form tailored to function. The fields to couple with the mechanical one include thermal, electric, magnetic, and chemical.To optimise the microscopic structure of a material one must have a robust and accurate continuum model that captures size effects. Linking the macroscopic and microscopic scales will be accomplished using a new class of micro-to-macro transition techniques for coupled problems - also termed computational homogenisation. The fundamental idea is to transfer information concerning the loading from the macroscopic scale down, and then to solve a problem at the microscopic scale that captures all the key features that give rise to coupling and size effects. The averaged (homogenised) response is then returned to the macroscopic scale. Following this approach, crude assumptions regarding the microscopic structure can be avoided leaded to more accurate and predictive simulations. The coupling of multiple fields across the scales is however very challenging and requires the development of new algorithms and continuum formulations. Optimisation theory allows one to design a component to maximise a certain function of interest subject to various constraints. The theory is relatively mature for engineered products at the macroscopic scale. This is not the case at the microscopic scale and certainly not the case for multiscale product design. The ability to optimally design and engineer active materials from the microscopic scale up will lead to a step-change in product functionality and design. The objective of the research is the enable this revolution through advanced algorithms and computational models.In addition to the stated scientific objectives, the research will underpin the formation of a new Centre of Excellence in Computational Engineering & Discovery. The Centre aims to promote mechanics in the UK by taking a leading role in the organisation of workshops and seminars, and through the education and development of postgraduate researchers.